Getting Exit Code 127 (Command not Found) from php exec()

Question

EDIT - Adding new info at the top for visibility. The www-data user can't use the exec() command. All attempts return a 127 error.

I setup a simple script that is just this

<?php
$res = exec("echo EXEC", $res1, $res2);
var_dump($res);
var_dump($res1);
var_dump($res2);
?>

When executed via the application (which of course runs as www-data) this returns the 127 error code.
When executed via this command it runs flawlessly sudo -u root php testExec.php
When executed via this command it again returns the 127 error code sudo -u www-data php testExec.php

Original Question

I can only seem to get the error code 127 back when trying to use the exec command in php. I'm trying to use the https://github.com/rialto-php/puphpeteer package to generate pdfs and it was working flawlessly but I can't find what changed that is causing it to fail now.

I've been using /usr/local/.nvm/versions/node/v14.2.0/bin/node as the path to node but I also tried copying it here /node/v16.14.2/bin so I could give the entire directory structure execute permissions. In either/both places node is owned by www-data (the user that php runs as) and has execute permissions (755).

Running '/node/v16.14.2/bin/node' '/var/www/html/vendor/nesk/puphpeteer/src/get-puppeteer-version.js' (the initial command that puphpeteer generates) from the command line works just fine and returns the expected result "5.5.0" so node is there and executable and the get-puppeteer-version script exists.

After troubleshooting that I decided to just test exec and discovered that that doesn't work for any commands. I've tried just running exec("date"); and exec("echo EXEC") and these also return the same exit code 127.

The disable_functions ini setting is empty (confirmed via empty result from ini_get('disable_functions')). Safe mode is not enabled (confirmed via false result from ini_get('safe_mode')).

If anyone has any insight into why exec won't work at all would be great!

Environment:
Ubuntu 18.04.4
PHP 8.1

Answer 1

So after further investigation.. I found that this was indeed a permissions issue. I had double checked that node and everything in the /bin folder had appropriate execute permissions..

What I had missed (and am not sure how it got changed) was that the /bin folder itself didn't have the appropriate execute permissions. Adding those immediately fixed my issue.